Facebook used details from address books to send invitation emails to non-members on behalf of its users.

Image: Facebook

Facebook is not allowed to use contacts from its members' address book to promote itself to non-members, Germany's top court has ruled.

The German Supreme Court confirmed two lower courts' earlier rulings that Facebook's friend-finder feature is illegal and amounts to "harassing advertising". The decision narrows the avenues Facebook and other online services have in expanding their networks.

Facebook's friend finder allows existing members to import their contacts to Facebook so that they can find friends on the network. However, Facebook used details from address books to send invitation emails to non-members on behalf of its users.

According to Spiegel Online, Facebook's lawyers had argued that it was merely providing technical assistance in sending emails on users' behalf and that the process was designed to help its users expand their social network, as opposed to Facebook's user base. Facebook also contended that the emails were not advertising, an argument the court did not accept.

The ruling stems from a complaint filed by the Federation of Germany Consumer Organizations (VZBZ) in 2010. The Berlin Regional Court ruled in 2012 the emails were illegal advertising since recipients hadn't consented to being contacted. Facebook's appeal was rejected in 2014.

"You can import your list of contacts from other places (ex: your email account, your phone) and we'll find your friends for you. After Facebook imports your contacts, you'll have the option to send a friend request to any of your friends that already have a Facebook account or send an invitation to friends who aren't on Facebook."